100% correct these are all good questions that need answering before starting any business, you have the horse in front of the cart 👍🏻and it is a very sensible reply to a not so smart question.
I think thai people in general are old fashioned, do right by them and they will do right by you, and foreigners have a bit of a advantage as they have a bit more cash to make life that little bit easier , but if she's pretending your not in a relationship with her, chances are it's strictly pretend and get the hell out of there.
yes mate my partner was refused first attempt but we put a second in straight away I sent a scaithing email to my solicitor in Bangkok he did the second application for free, because the person handling it did not include half of the information I supplied the second application was approved 6 weeks after the 1st one was rejected. Don't give up there just seeing if your committed 🤣seriously.
Peter the Australian government is super strict when it comes to visas for thai people, but the more information you give them the better the chance of being approved, so don't stress about a specific figure, they just need to know it is a real relationship, and you can afford to look after her for the duration of the holiday and most of all that there are reasons (example; own a house, have children there, have a job etc etc ) that she will definitely return to thailand once the visa is approved, while the questions sound intrusive which they are, provide them with everything plus some (photos, dates,facebook msg) everything to prove it's real.